Art op cracking hydrocarbons



Patented Nov. 22, 1927.

J UNITED STATES;

PATENT ',oFFlca EDWARD w; rsoivr, onwrivnnrna, ILLINOIS, AssrGNon rosrncrninnsrrnrne coivr-` e 1 PANY; or onrcaeo,`inr,rnors, iroonronarron`or MAINE.

ART 0F CRACKING HYDHOGAR/ZBONS.,`

1 implicationnieafinuaryl28, lesa ,serial No.53a351.

\ In the usual practice 'otcrackinghydro carbon. oils7 gas oil, fueloilor other oil containing *y heavier. l hydrocarbons. is" heatedheavier components, such as are:unsuitable as components otgasoline orother desired distillate,` are condensed and` flow baclr into the. bodyof oil in the still where they inter-I mingle with the contents of thestill and undergo further treatment. .The vapors oi oils ot the desiredcharacter pass over troni the top of' the reflux tower to a condenserwhere the condensate is condensed and from which they are discharged.together with fixed gases into `a receiving drum `troni which thecondensates are led to `suitable storage tanks and the surplus gases togas i holders or burners. e D

It is necessary that-a predeterminedtem perature be approximatelymaintained at the head or top of the reflux tower in lorder to avoidcondensing therein vapors which are suitable `for the gasoline or otherlight prod'- uctwhich is to bedmade and whiclnit condensed within thetower, would be returned tothe still and resubmitted to the crackingtemperature and more or less broken down. into lixed gas. `As thereiiuzrtowery necesr sarily radiates considerable, heat, alarge amount of heatmust be` suppliedto the tower .in order to maintain the headntem-i`perature and this has been done through the medium of the vapors`theiznselves thus .putting a considerable additional. burden upon theheating means vfor the still `increasing the `fuel consumption andreducing the outa. put. Furthermore, where the distillation takes placeentirely under the pressureot the vapors generated, it is necessary tomaintain the still charge at ahigh temperature, towit, the criticaltemperature of the liquid. underthe highpressure of its vapors.Theipractce, in some systems of distillation, is to lower thedistillation point ot the oilby partial `pressure produced bysteani, thesteam ordinarily being .introducedba neath kthe surface ofthe liquid,thus reduc#y ing the temperature required, This has .the

disadvantage; among othersythat the steam entraine considerable oftheoil which is too heavy tube properly included within thef product koitthewoperation and carries it I over into the `r condenser, andfurthermore the presence or' the steam,wh1ch,condensesat. a temperaturewithin thecondensing range( @if the desired; rwdutsnf the @rammenta/Putsa.{ heavy,'additional'burden*A upon the conf denser requiring itto be ofvery materially increased size. v 'Y l n Y y n i lt has also beenproposed to introduce an inert gas into the stillffor lthe purpose ot"-controlling the pressure therein and in case` the fixed lgases developedin the still provide a pressure in excess of that desiredlto releasesuilicient gas to lower therpressure to thel required degree. f y f r Myinvention involves vintroducing into and mingling with vthe vaporsevolved from the still and passing Y, through vthe reluX tower acontinuous stream of gas sutlieient in. amount notz only to lcontrol thepressure in, the still irrespective `*of 'the development 4 of vaporstherebyrbut also to assist incajrrying the yvapors ofy lthe desireddistillate through theL reflui; towerto'thegcondenser whilerintroducingoil to be supplied to the operation into the reflux` tower indirectcontacte with fthewvaporsrand gases therein thereby absorbing a largepart of the heat givenjoi inthe reiuxing operation in this o.il. g4 Thepressure, beingjdependent on the introduced gases, is not subject totheirregularities incident to pressure maintained ,by the evolved vaporsoccasioned by variations in evolutioiji and condensation. The stream ofgas being continuously introduced, rpreierably at the bottom of thereflux tower, and continuously exhausted, preferably beyond thecondenser, carries thelvapors with it up the tower thus reducing lthehead temperature required to e'ect the desired cutbetween the heavieroils which are returned',y to the still torbe recracked and thelighterdistillate which passes over to thecondenser; @GoolV or unheatedgases are Vused with advantage yassisting in cooling and condensing tthe heavier reflux lvapors thus reducingthe required capacity of theyredux tower. Preferably the gases employed are hydrogencontaining orhydrocarbon gases and itis convenientand desirable to employ for thepurpose the liXed gases given;y od theA still orlbya group of stills Byemploying fresh stock into the upper end of the tower directly into thevapor space therein and in direct contact with the vapors, and means forintroducing gas into the lower end of the tower directly into the vaporspace therein.

2.k In combination in a pressure still system for cracking oil, apressure still, a reflux tower in free communication therewith throughconnections for conveying vapors from the still to the tower and liquidtrom the tower to the still, a condenser and connections-for conveyingvapors from the tower to the condenser, means for maintainingsupcratmospheric pressure on the still and through the tower, means'forfeeding fresh stock into theupper end of the tower di `rectly into thevapor space therein, and

means for reintroducing into the lower end of the tower directly intovthe vapor spare therein gas escaping from the condenser uncondensed.

3. In combination in a pressure still sys-r tem for cracking oil, apressure still, a reflux tower in free communication therewith throughconnections for' conveying vapors from the still to the tower and liquidfrom the tower to the still, a condenser and connections for maintainingsuperatniospheric pressure on the still and through the tower, means forfeeding fresh stock into the upper end of the towerdirectly into thevapor space therein and in direct contact with the vapors, and means forintroducing hydrocarbon gases into the lower end of the tower directlyinto the vapor space therein.

l. In combination in a pressure still sys tem for cracking` oil, astill, a reflux tower,

a condenser and connections between the still,

tower and condenser', means for feeding fresh stock into the upper endof the tower di rectly into the vapor space therein and in directcontact with the vapors and means for introducing gas into the lower endof the tower directly into the vapor space th erein,

5. A process for cracking hydrocarbon oils, comprising heating the oilto a cracking temperature under pressure in a still, pass' 6.1i processfor cracking hydrocarbonoils, comprising heating the oil to a crackingtemperature under pressure ina still, passing vapors from the stillthrough a redux tower, feeding fresh stock into the upper end of thetower in direct contact with the vapors therein, introducing a cool'stream of uncondensed still gas into ther lower end of the tower indirect contact with the vapors therein, and conveying fresh stock andreflux condensate from the lower end ofthe tower to the still.

7. A process for cracking hydrocarbon oils, comprising heating the oilto a cracking temperature under pressure in a still, passing vapors fromthe still ythrough a reflux tower, maintaining substantially the stillpressure through the tower, feeding fresh stock into the upper end ofthe tower in direct contact with the vapors therein, introducing coolhydrocarbon gases into the lower end of the tower in direct contact withthe vapors therein, and conveying fresh stock and reflux condensate fromthe lower end of the tower to the still.y

8. A process for cracking hydrocarbon oils, comprising heating the oilto a cracking temperature under pressure in a still, passing vapors fromthe still through a reflux tower, feeding fresh stock into the upper endof the tower in direct contact with the vapors therein, introducing anunheated stream of gas into the lower end of the tower in direct contactwith the vapors therein, and conveying admixed fresh stock and refluxcondensate from the lower end of the tower to the still.

EDWARD W. ISOM.

